Pralmorelin-containing nasal drop preparations

ABSTRACT

The preparation for intranasal administration comprising D-alanyl-3-(naphthalen-2-yl)-D-alanyl-L-alanyl-L-tryptophyl-D-phenylalanyl-L-lysinamide (pralmorelin) and/or an acid addition salt thereof as an active ingredient and water permits a marked increase in the in vivo absorption of pralmorelin and hence provides adequate efficacy even if it is administered in a small dose at a time. The preparation also allows pralmorelin to be dissolved in an increased amount, so it can be formulated pharmaceutically with great ease. It also high stability over time.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a 371 National Phase Entry of co-pendingInternational Application No. PCT/JP01/04503, filed May 29, 2001, whichdesignated the U.S. and which claims the benefit under 35 U.S.C. § 119of Japanese Application No. 158676/2000, filed May 29, 2000.

TECHNICAL FIELD

This invention relates to preparations for intranasal administrationcontainingD-alanyl-3-(naphthalen-2-yl)-D-alanyl-L-alanyl-L-tryptophyl-D-phenylalanyl-L-lysinamide(hereunder sometimes abbreviated as pralmorelin) which is a kind ofgrowth-hormone releasing peptide (hereunder sometimes abbreviated asGHRP). More specifically, the invention relates to a formulation thatincreases the in vivo absorption of pralmorelin, as well as apreparation for intranasal administration of pralmorelin that enablesincreasing the concentration of pralmorelin in the preparation.

BACKGROUND ART

The secretion of growth hormone is known to be regulated by agrowth-hormone releasing factor in the hypothalamus and a growth-hormonerelease inhibiting factor somatostatin. In the case of humans, thegrowth-hormone releasing factor (hereunder sometimes abbreviated asGHRH) in the hypothalamus is a peptide having about 40 amino acidresidues and several types including one separated and purified fromhuman cells and one synthesized with a peptide synthesizer have begun tobe used as an in vivo diagnostic or a therapeutic of dwarfism. However,the method involving separation and purification from human cells hasthe problem of limited productivity whereas the synthesis method whichrequires condensation of almost 40 amino acids is not only cumbersome inoperation but also time-consuming and less cost-effective.

Development and research has therefore been made of peptides thatconsist of a shorter chain of amino acids, that are easy to synthesizeand that promote the secretion of growth hormone. As a result,growth-hormone releasing peptides such as pralmorelin have beendeveloped as therapeutics of hypothalamic or pituitary dwarfism ordiagnostics of pituitary functions (JP 7-507039 A (Kohyo) and JP10-45619 A (Kokai)).

It has been known that those growth-hormone releasing peptides (GHRPs)share no structural homology with GHRH but that their effects on therelease of growth hormone are similar, except for the mechanism ofactions they exhibit. A recent report also discloses that whereas GHRHhas only direct action on the secretion of growth hormone in thepituitary, GHRPs not only directly affect the secretion of growthhormone in the pituitary but also show GHRH secreting action in thearcuate nucleus and somatostatin secretion inhibiting action in theperiventricular nucleus.

Thus, because of these differences in structure and mechanism of action,there is a need to study the method of applying GHRPs such aspralmorelin aside from the application method for GHRH. In the past,pralmorelin has primarily been administered as an injection. However,there is a demand for the development of preparations that impose lessstress on patients and pralmorelin has recently been shown to beeffective in intranasal administration (Journal of ClinicalEndocrinology and Metabolism, Vol. 80, No. 10, pp. 2987–2992 (1995),Journal of Endocrinology, 155, pp. 79–86 (1997) and Xenobiotica, Vol.28, No. 11, 1083–1092 (1998)).

The reported preparations for intranasal administration usephysiological saline as a solvent. This is because the preparations forintranasal administration which are applied to the nasal mucosa arecommonly rendered isotonic with physiological saline in order to reduceirritation. However, in the case of pralmorelin, the use ofphysiological saline as a solvent presents the following problems and itis difficult to formulate it pharmaceutically.

To be more specific, pralmorelin has low saturated solubility inphysiological saline (0.15 w/v % at 25° C. when it is dihydrochloride)and at higher concentrations, pralmorelin becomes insoluble with thelapse of time and a problem occurs in terms of storage stability, thusmaking it difficult to formulate pralmorelin pharmaceutically usingphysiological saline. Even at concentrations lower than its saturatedsolubility, pralmorelin has low in vivo absorption and needs frequentadministration.

Hence, no pralmorelin preparations have ever been made practicable usingphysiological saline.

In view of these, in order to develop pralmorelin preparations forintranasal administration, it is essential to increase the absorptionand concentration of pralmorelin in the preparation and there is anurgent need to develop preparations that are improved in those aspects.It is also indispensable to provide pralmorelin preparations forintranasal administration that ensure high stability over time inpractical applications.

An object, therefore, of the invention is to increase the in vivoabsorption of pralmorelin.

Another object of the invention is to provide a pralmorelin preparationfor intranasal administration having higher concentration thanpreparations using physiological saline. Since inorganic salts formerlyused as osmolarity moderators lower the solubility of pralmorelin, thepresent inventors made intensive studies including the choice of usefulosmolarity moderators other than the inorganic salts.

Still another object of the invention is to obtain industrially feasiblepralmorelin containing preparations for intranasal administration and todesign practically feasible formulations.

DISCLOSURE OF THE INVENTION

Under the above-described circumstances, the present inventors took toworking on pralmorelin preparations for intranasal administration andmade various studies. As a result, they found that preparationscomprising water and pralmorelin and/or acid addition salts thereof(preferably water and acid addition salts of pralmorelin) without usingheretofore common physiological saline achieved higher in vivoabsorption of pralmorelin and higher solubility of pralmorelin than whenphysiological saline was used, thus assuring better stability over timeas preparations. It was also found that pralmorelin preparations forintranasal administration which were rendered isotonic with at least oneosmolarity moderator selected from non-electrolytes such as sugaralcohols, sugars and alcohols achieved higher absorption of pralmorelinthan preparations that were rendered isotonic with physiological saline.The inventors also found that when such osmolarity moderators wereincorporated, the absorption of pralmorelin increased at low osmoticpressure. Furthermore, as regards the relationship between theconcentration of pralmorelin in the preparation of the invention forintranasal administration and the in vivo absorption of pralmorelin, theinventors found that the in vivo absorption of pralmorelin increasedmarkedly as its concentration increased. Therefore, the preparation ofthe invention brings about adequate efficacy even if the dose ofpralmorelin administered at a time is smaller than in the case of theconventional preparations using physiological saline. In short, thepresent inventors found practically feasible pralmorelin preparationsfor intranasal administration featuring improved absorption ofpralmorelin.

Hence, the present invention provides a preparation for intranasaladministration comprisingD-alanyl-3-(naphthalen-2-yl)-D-alanyl-L-alanyl-L-tryptophyl-D-phenylalanyl-L-lysinamideand/or an acid addition salt thereof as an active ingredient, and water.

BEST MODE FOR CARRYING OUT THE INVENTION

The following are preferred embodiments of the invention.

According to an embodiment of the invention, there is provided apreparation for intranasal administration consisting essentially ofD-alanyl-3-(naphthalen-2-yl)-D-alanyl-L-alanyl-L-tryptophyl-D-phenylalanyl-L-lysinamideand/or an acid addition salt thereof as an active ingredient, and water.

According to another embodiment of the invention, there is provided theabove-described preparation for intranasal administration, in which theactive ingredient is an acid addition salt ofD-alanyl-3-(naphthalen-2-yl)-D-alanyl-L-alanyl-L-tryptophyl-D-phenylalanyl-L-lysinamide.

According to another embodiment of the invention, there is provided theabove-described preparation for intranasal administration, in which theacid addition salt is hydrochloride.

According to another embodiment of the invention, there is provided theabove-described preparation for intranasal administration, in which theactive ingredient isD-alanyl-3-(naphthalen-2-yl)-D-alanyl-L-alanyl-L-tryptophyl-D-phenylalanyl-L-lysinamidedihydrochloride.

According to another embodiment of the invention, there is provided theabove-described preparation for intranasal administration, which furthercontains a non-electrolyte.

According to another embodiment of the invention, there is provided theabove-described preparation for intranasal administration, in which thenon-electrolyte is at least one member of the group consisting of sugaralcohols, sugars and alcohols.

According to another embodiment of the invention, there is provided theabove-described preparation for intranasal administration which has anosmolarity ratio of not more than about 1.

According to another embodiment of the invention, there is provided theabove-described preparation for intranasal administration which has anosmolarity ratio of from not less than about 0.01 to not more than about0.5.

According to another embodiment of the invention, there is provided theabove-described preparation for intranasal administration which furthercontains at least one antiseptic selected from quaternary ammonium saltsand parabens.

According to another embodiment of the invention, there is provided theabove-described preparation for intranasal administration, in which theconcentration of the active ingredient is from about 0.05 to about 1.5w/v %.

According to another embodiment of the invention, there is provided theabove-described preparation for intranasal administration which has a pHof from about 4 to about 7.

According to another embodiment of the invention, there is provided theabove-described preparation for intranasal administration which is asprayable solution.

Acid addition salts of pralmorelin are used more preferably than itsfree form in view of the solubility of pralmorelin. Examples of acidsthat can form acid addition salts include inorganic acids such ashydrochloric acid, sulfuric acid, hydrobromic acid, phosphoric acid andnitric acid, organic acids such as formic acid, acetic acid, propionicacid, succinic acid, glycolic acid, lactic acid, malic acid, tartaricacid, citric acid, maleic acid, phthalic acid, phenylacetic acid,benzoic acid, salicylic acid, methanesulfonic acid, toluenesulfonicacid, benzenesulfonic acid, oxalic acid and trifluoroacetic acid, andamino acids such as aspartic acid and glutamic acid. Among these acids,those which can form pharmaceutically acceptable acid addition salts arechosen as appropriate.

Preferred acid addition salts are hydrochlorides and dihydrochloridesare more preferred.

The preparations of the invention may employ pralmorelin in combinationwith one or more acid addition salts thereof.

As used in the preparations of the invention, “water” means any waterthat is conventionally used in pharmaceutical formulating of medicinesas exemplified by tap water, distilled water and purified water;distilled water and purified water are preferred.

For the preparations of the invention, the combination of pralmorelinand/or acid addition salts thereof with water is the most preferred fromthe viewpoint of in vivo absorption of pralmorelin. If desired,auxiliary agents such as osmolarity moderators, preservatives anddispersants may be employed. As already mentioned, the preparations ofthe invention should not contain inorganic salts at 0.9 w/v % or higherconcentrations which are common in physiological saline becauseabsorption of pralmorelin is impaired; it should however be noted thatvery small amounts of inorganic salts may be contained.

Osmolarity moderators that may be employed in the preparations of theinvention are those which are commonly used as isotonization agents inpharmaceuticals; from the viewpoints of solubility and in vivoabsorption, they are preferably non-electrolytes as exemplified by sugaralcohols, sugars and alcohols; one or more of these non-electrolyticosmolarity agents may be used.

Sugar alcohols encompass not only straight polyhydric alcohols obtainedby reducing the carbonyl groups in sugar but also cyclic alcohols;examples include D-mannitol, xylitol, galactitol, glucitol, inositol,D-sorbitol, etc. and preferred examples include D-manntiol, xylitol andD-sorbitol. Alcohols include glycerin.

Sugars encompass monosaccharides, oligosaccharides and polysaccharides;examples include glucose, fructose, sucrose, maltose and lactose andpreferred examples include glucose, fructose, sucrose and maltose.

If an additive, in particular, an osmolarity moderator, is used in thepralmorelin preparation of the invention for intranasal administration,its content is preferably the smaller from the viewpoint of pralmorelinabsorption and the osmolarity ratio is preferably about 1.2 or less,more preferably about 1 or less, even more preferably about 0.8 or less,and most preferably between about 0.01 and about 0.5. The term“osmolarity ratio” as used in the invention is expressed by a relativeratio based on physiological osmotic pressure. Stated specifically, itmeans an osmolarity ratio as determined by calculation for theconcentration of sodium chloride, with the osmolarity ratio of anaqueous solution of 0.9 w/v % sodium chloride being taken as 1. Even ifan osmolarity ratio of 1 is obtained by using one of thenon-electrolytic osmolarity moderators listed above, the in vivoabsorption of pralmorelin can be increased compared to the case ofobtaining isotonicity with sodium chloride and this has been verified inthe experiments to be described later.

Antiseptics that can be used in the invention include quaternaryammonium salts such as benzalkonium chloride and benzethonium chloride,as well as parabens including methyl paraoxybenzoate, ethylparaoxybenzoate, propyl paraoxybenzoate, butyl paraoxybenzoate, etc. Oneor more of these ingredients may be used in the invention.

Pralmorelin or salts thereof may be incorporated in the preparations insuch amounts that their concentration is preferably about 0.05 w/v %upward, more preferably between about 0.05 and about 1.5 w/v %, evenmore preferably between about 0.05 and about 0.30 w/v %, and mostpreferably between about 0.05 and about 0.15 w/v %. More preferred arepralmorelin preparations for intranasal administration that are adjustedto have pH between about 4 and about 7.

The preparations of the invention may be administered at doses that canbe adjusted as appropriate for the severity of the disease, the age ofthe patient, his or her body weight and the symptom manifested. For asingle administration, the dose is preferably between about 0.1 andabout 100 μg per kg of body weight, more preferably between about 0.5and about 10 μg per kg of body weight, if pralmorelin dihydrochloride isto be administered. The preparations of the invention are preferablyadministered once to four times daily and a single dosage may be appliedto one or both nostrils. For a single administration, the volume ispreferably between about 50 and about 200 μl per nostril, morepreferably about 100 μl per nostril.

The preparations of the invention may take any form without particularlimitations and ordinary forms may be adopted that are conventional topreparations for intranasal administration, as exemplified by drops,sprayable solutions (e.g. liquids and aerosols that can be sprayed withnebulizers), washes, infusions, etc. From the viewpoint of conveniencein handling, the preferred form is such that the preparation iscontained in a vessel that needs to be pushed once to release apredetermined amount of the active ingredient. In the case of sprayablesolutions, particles sprayed preferably have an average size betweenabout 30 and about 70 μm.

The following preparations and examples are provided for the purpose offurther illustrating the present invention but are in no way to be takenas limiting.

Preparations

Preparations for intranasal administration that contained 0.1 w/v %pralmorelin were formulated using distilled water as a solvent,pralmorelin dihydrochloride as the active ingredient (it was prepared bythe method described in JP 7-507039 A (kohyo) and the same compound wasused in the following examples), and benzalkonium chloride as anantiseptic (Table 1). The preparations were measured for pH andosmolarity ratio in accordance with General Test Methods in the JapanesePharmacopoeia (Table 1).

TABLE 1 Concentration Concentration of pralmorelin of additiveOsmolarity (w/v %) (w/v %) pH Ratio 0.1 benzalkonium chloride 5.7 0.02(0.005) 0.1 benzalkonium chloride 5.8 0.02 (0.01) Benzalkonium chloride(50 w/v % conc. sol.): product of Maruishi Pharmaceutical Co., Ltd.

The average particle size of each preparation for its use as a sprayablesolution was measured as follows. The preparation shown in Table 1 whichcontained 0.1% (w/v) of pralmorelin dihydrochloride and 0.005% (w/v) ofbenzalkonium chloride was sprayed with a nebulizer for intranasaladministration (New Nosuran bottle with a capacity of 10 ml; product ofShinko Kagaku K.K.) and subjected to measurement of average particlesize with a particle size analyzer operating on the scattering of laserlight (Model LDSA-1400A; product of Tonichi Computer Applications); theresult was 65 μm.

EXAMPLE 1

With an isotonic solution (in distilled water) of 5 w/v % D-mannitol orphysiological saline used as a solvent, a solution of 0.1 w/v %pralmorelin dihydrochloride was prepared and administered to male rats(7-week old, Crj:CD (SD) strain, N=3) in an amount of 50 μg/kg.

With the rats fixed supine under an unanesthetized condition, thepralmorelin solution was administered into one nostril of each rat in anamount of 50 μg/kg with a micropipette. The rats were not anesthetizedfor two reasons: actual drug administration is effected withoutanesthesia; the effects anesthetization would have on drug absorptionhave not been elucidated.

The concentration of an unchanged substance in plasma was measured inaccordance with the two-antibody competition method of Kitagawa et al.summarized below [J. Assoc. Off. Anal. Chem., Vol. 68, No. 4, pp.661–664 (1985) and J. Immunological Methods, 72, pp. 109–118 (1984)].

Anti-rabbit IgG goat IgG (Jackson Immuno Research) as the secondantibody was adsorbed on an ELISA 96-well microplate (GREINER). Then,anti-pralmorelin dihydrochloride rabbit serum was adsorbed on the samemicroplate; the serum was the first antibody and had been obtained bysubcutaneous injection of rabbits with an immunogen having pralmorelindihydrochloride bound to bovine serum albumin (Sigma) by means ofwater-soluble carbodiimide (Nakarai Tesk).

Pralmorelin dihydrochloride contained in a sample was allowed to competefor pralmorelin labeled β-galactosidase that had been crosslinked withcrosslinker N-(m-maleimidebenzoyloxy)succinimide (Nakaral Tesk); then,the β-galactosidase bound to the first antibody was reacted with4-methylumbelliferyl-β-D-galactopyranoside; thereafter, the enzymaticactivity of the β-galactosidase bound to the first antibody was measuredat an excitation wavelength of 370 nm and a fluorescence wavelength of460 nm.

From the measured values for the enzymatic activity of theβ-galactosidase, the maximum plasma drug concentration (Cmax) ofpralmorelin dihydrochloride, the area under the plasma drugconcentration vs time curve (AUC) and the bioavailability (the ratio ofAUC obtained by intranasal administration to AUC obtained by intravenousadministration) were obtained.

As a result, it was found that the solution for intranasaladministration that had been rendered isotonic with mannitol was morereadily absorbed in vivo than the one rendered isotonic withphysiological saline (Table 2).

TABLE 2 Comparison of two solvents, physiological saline and 5 w/v %D-mannitol Cmax AUC Bioavailability (ng/ml) (ng · hr/ml) (%)Physiological saline 0.70 1.98 3.08 5% D-mannitol 2.37 2.71 4.22

EXAMPLE 2

A preparation for intranasal administration containing 0.3 w/v %pralmorelin was prepared using distilled water as a solvent, pralmorelindihydrochloride as the active ingredient and benzalkonium chloride as anantiseptic (Table 3). Another preparation for intranasal administrationcontaining 0.3 w/v % pralmorelin was prepared in the same manner exceptthat it further contained D-mannitol as an osmolarity moderator (Table4). The two preparations were filled into glass ampules and each storedat 50° C. and 60° C. under light-tight conditions for 2 weeks. Initiallyand after 2 weeks, each solution was checked for the appearance, pH,osmolarity ratio, pralmorelin content (residual) and purity (Tables 5and 6). The appearance of each solution was observed in accordance withGeneral Rule 21 in the 13^(th) Revised Japanese Pharmacopoeia.Measurements of pH and osmolarity ratio were conducted in accordancewith General Test Methods in the Japanese Pharmacopoeia. Measurements ofpralmorelin content and purity were conducted by liquid chromatography.

As a result, it became clear that whether D-mannitol was contained ornot, the use of pralmorelin and distilled water enabled the making ofpreparations for intranasal administration that contained pralmorelin ata concentration of 0.3 w/v % which was higher than 0.15 w/v % (25° C.),i.e., the saturated solubility in physiological saline. The preparationshad high stability over time.

TABLE 3 Ingredients and their contents in pralmorelin preparation forintranasal administration Content Ingredient (w/v %) Pralmorelindihydrochloride 0.3 Benzalkonium chloride 0.01 Distilled water q.s.

TABLE 4 Ingredients and their contents in pralmorelin preparation forintranasal administration containing D-mannitol Content Ingredient (w/v%) Pralmorelin dihydrochloride 0.3 D-mannitol 5 Benzalkonium chloride0.01 Distilled water q.s. D-mannitol: product of Kyowa Hakko Kogyo Co.,Ltd. Benzalkonium chloride (50 w/v % conc. sol.): product of MaruishiPharmaceutical Co., Ltd.

TABLE 5 Stability of pralmorelin preparation for intranasaladministration Parameter Initial 50° C. × 2 wk 60° C. × 2 wk Appearancecolorless and colorless and colorless and clear liquid clear liquidclear liquid pH 5.05 5.63 5.72 Osmolarity ratio 0.03 0.03 0.03 Content(%) 100 100 99.3 Purity (%) 99.0 98.8 98.3

TABLE 6 Stability of pralmorelin preparation for intranasaladministration containing D-mannitol Parameter Initial 50° C. × 2 wk 60°C. × 2 wk Appearance colorless and colorless and colorless and clearliquid clear liquid clear liquid pH 5.35 5.67 5.52 Osmolarity ratio 1.051.05 1.04 Content (%) 100 100 99.3 Purity (%) 99.0 98.4 98.4

EXAMPLE 3

Since it was found to be possible to use D-mannitol as an osmolaritymoderator, a test was made to check whether formulations would befeasible using other non-electrolytic osmolarity moderators.

Pralmorelin dihydrochloride (0.3 g) and D-mannitol (5 g) were dissolvedin purified water (ca. 90 mL); after adding 1 mL of a solutioncontaining 50 w/v % benzalkonium chloride, purified water was added tomake 100 mL; the resulting solution was filtered to make a preparationfor intranasal administration of pralmorelin (pralmorelindihydrochloride, 0.3 w/v %; D-mannitol, 5 w/v %; benzalkonium chloride,0.5 w/v %).

With this method used as a basic technique, pralmorelin preparations forintranasal administration were made according to the formulations shownin Table 7 and measured for pH and osmolarity ratio by the same methodsas in Example 1.

As a result, it became clear that the use of non-electrolytic osmolaritymoderators other than D-mannitol enabled the making of preparations forintranasal administration that contained pralmorelin at a concentrationof 0.3 w/v % which was higher than 0.15 w/v % (25° C.), i.e., thesaturated solubility in physiological saline.

TABLE 7 Pralmorelin preparations for intranasal administrationcontaining various non-electrolytes Concentration Concentrations ofpralmorelin of additives Osmolarity (w/v %) (w/v %) pH ratio 0.3D-mannitol (5)   5.6 1.0 benzalkonium chloride (0.5) 0.3 xylitol (5)  5.7 1.2 benzalkonium chloride (0.5) 0.3 glucose (5)   5.4 1.0benzalkonium chloride (0.5) 0.3 fructose (5)   5.7 1.0 benzalkoniumchloride (0.5) 0.3 D-sorbitol (5)   5.5 1.0 benzalkonium chloride (0.5)0.3 sucrose (9.3) 5.6 1.0 benzalkonium chloride (0.5) 0.3 glycerin (2.6)5.6 1.1 benzalkonium chloride (0.5) 0.3 maltose (10)   5.2 1.0benzalkonium chloride (0.5) 0.3 D-mannitol (2.5) 5.6 0.5 benzalkoniumchloride (0.5) 0.3 D-mannitol (1.5) 5.7 0.3 benzalkonium chloride (0.5)D-mannitol: product of Kyowa Hakko Kogyo Co., Ltd. Benzalkonium chloride(50 w/v % conc. sol.): product of Maruishi Pharmaceutical Co., Ltd.Xylitol: product of Wako Pure Chemical Industries, Ltd. Glucose: productof Otsuka Pharmaceutical Co., Ltd. Fructose: product of Wako PureChemical Industries, Ltd. D-sorbitol: product of Junsei Pure ChemicalCo., Ltd. Sucrose: product of Sanko Seiyaku Kogyo K.K. Glycerin: productof Wako Pure Chemical Industries, Ltd. Maltose (monohydrate): product ofWako Pure Chemical Industries, Ltd.

EXAMPLE 4

Two kinds of preparation for intranasal administration, one consistingof pralmorelin dihydrochloride and distilled water and the other furthercontaining D-mannitol at varying concentrations, were evaluated fortheir effects on in vivo absorption of pralmorelin dihydrochloride. Withfour kinds of solvent, distilled water, 2.5 w/v % D-mannitol solution(osmolarity ratio, 0.5), 5 w/v % D-mannitol solution (osmolarity ratio,1), 10 w/v % D-mannitol solution (osmolarity ratio, 2), solutions of 0.4w/v % pralmorelin dihydrochloride were prepared and administered in anamount of 50 μg/kg to male rats as in Example 1. As a result, thefollowing two observations were obtained: the highest absorption ofpralmorelin was exhibited by the preparation for intranasaladministration that consisted of pralmorelin dihydrochloride anddistilled water; when D-mannitol was added, the in vivo absorption ofpralmorelin dihydrochloride improved as the solution contained lessD-mannitol, or became hypotonic.

Conventionally, absorption promoters such as surfactants were added tophysiological saline in order to enhance the absorption of preparationsfor intranasal administration. However, it was verified that thepreparation for intranasal administration which contained only distilledwater besides pralmorelin dihydrochloride exhibited very high absorptionof the active ingredient even when no absorption enhancer was used; itwas also verified that even when a non-electrolytic osmolarity moderatorwas used, the in vivo absorption of pralmorelin dihydrochloride could beincreased by just reducing the concentration of the non-electrolyticosmolarity moderator to render the solution hypotonic (Table 8).

TABLE 8 Bioavailability with distilled water or D-mannitol atconcentrations of 2.5, 5 and 10% Cmax Bioavailability (ng/ml) (%)Distilled water 60.7 26.2 D-mannitol 55.8 22.1 2.5 (w/v %) D-mannitol49.2 19 5 (w/v %) D-mannitol 21.7 9 10 (w/v %)

EXAMPLE 5

With an aqueous solution of 0.005 w/v % benzalkonium chloride used as abase, pralmorelin preparations for intranasal administration were madeat three concentrations, 0.1 w/v %, 0.3 w/v % and 1.0 w/v %, ofpralmorelin dihydrochloride. Each preparation was dripped into the rightnostril of 5-week old male Crj:CD (SD) rats (N=3). The dose ofadministration was 0.1 mg/kg, 0.3 mg/kg and 1.0 mg/kg for the respectivepreparations, which were all administered in a volume of 0.1 ml/kg.

As a result, it was found that when the same volume of pralmorelindihydrochloride was administered intranasally, an increase in theconcentration of pralmorelin in the administered solution allowed the invivo absorption of pralmorelin to increase markedly beyond the valueanticipated from the proportional relationship with its concentration(Table 9).

TABLE 9 Dose Tmax Cmax AUC (mg/kg) (hr) (ng/ml) (ng · hr/ml) 0.1 0.1718.04 14.54 0.3 0.17 72.85 48.14 1.0 0.17 501.83 250.05 (In the table,Tmax represents the time to the showing of maximum plasmaconcentration.)

INDUSTRIAL APPLICABILITY

The preparations of the invention for intranasal administration thatcomprise water and pralmorelin or acid addition salts thereof(preferably water and acid addition salts of pralmorelin) achieve betterin vivo absorption of pralmorelin than the conventional preparationsusing physiological saline and an increase in the concentration ofpralmorelin in the preparations for intranasal administration allows thein vivo absorption of pralmorelin to increase markedly beyond the valueanticipated from the proportional relationship with its concentration.Therefore, compared to the conventional preparations using physiologicalsaline, the preparations of the invention achieve adequate efficacy evenif the dose of pralmorelin administered at a time is small. In addition,compared to the conventional preparations using physiological saline,the preparations of the invention for intranasal administration permitpralmorelin to be dissolved in an increased amount and, hence, can beformulated pharmaceutically with great ease. Further, the preparationsof the invention for intranasal administration have very high stabilityover time as pharmaceutical products. As a result of these advantages,the present invention enables the production of practically feasiblepralmorelin preparations for intranasal administration that have asimple enough formulation.

1. A preparation for intranasal administration which comprisesD-alanyl-3-(naphthalen-2-yl)-D-alanyl-L-alanyl-L-tryptophyl-D-phenylalanyl-L-lysinamideand/or an acid addition salt thereof as an active ingredient, and water,and has an osmolarity ratio of from not less than 0.01 to not more thanabout 0.5.
 2. The preparation for intranasal administration of claim 1wherein said active ingredient is an acid addition salt ofD-alanyl-3-(naphthalen-2-yl)-D-alanyl-L-alanyl-L-tryptophyl-D-phenylalanyl-L-lysinamide.3. The preparation for intranasal administration according to claim 2,wherein said acid addition salt is hydrochloride.
 4. The preparation forintranasal administration according to claim 3, wherein said activeingredient isD-alanyl-3-(naphthalen-2-yl)-D-alanyl-L-alanyl-L-tryptophyl-D-phenylalanyl-L-lysinamidedihydrochloride.
 5. The preparation for intranasal administrationaccording to claim 1, which further contains at least one antisepticselected from quaternary ammonium salts and parabens.
 6. The preparationfor intranasal administration according to claim 1, wherein theconcentration of said active ingredient is from about 0.05 to about 1.5w/v %.
 7. The preparation for intranasal administration according toclaim 1, which has a pH of from about 4 to about
 7. 8. The preparationfor intranasal administration according to claim 1, which is a sprayablesolution.
 9. The preparation for intranasal administration according toclaim 1, which further contains a non-electrolyte.
 10. The preparationfor intranasal administration according to claim 9, wherein thenon-electrolyte is at least one member selected from the groupconsisting of sugar alcohols, sugars and alcohols.
 11. The preparationfor intranasal administration according to claim 9, which furthercontains at least one antiseptic selected from quaternary ammonium saltsand parabens.
 12. The preparation for intranasal administrationaccording to claim 9, wherein the concentration of said activeingredient is from about 0.05 to about 1.5 w/v %.
 13. The preparationfor intranasal administration according to claim 9, which has a pH fromabout 4 to about
 7. 14. The preparation for intranasal administrationaccording to claim 9, which is a sprayable solution.